For all of the centuries human beings fantasized about traveling in space, no one gave much thought to the business of communicating with Earth. Compared to the job of building the spacecraft and getting it off the ground, figuring out some way to stay in touch with home seemed like the easy part.
Things turned out to be a lot more complicated than that—not just because of the enormous distances that would have to be covered (Voyager 1 is currently 11.8 billion miles, or 19 billion km, from Earth), but because space is a three-dimensional place. Signals could be coming in from any and all directions and, making matters worse, the Earth is spinning. An antenna that has a lock on a spacecraft at noon will be facing the opposite way by midnight.
For that reason, in December 1963, the Deep Space Network (DSN) went online, a web of three sets of antennae at three distinct sites on the planet: Goldstone, in California; Madrid, Spain; and Canberra, Australia. At no point would any Earthly spacecraft at any spot in the cosmos have to be out of touch. The DSN turned 50 last month, and while it’s been upgraded and improved over the decades, its mission has remained the same. Virtually any grand space picture you’ve ever seen from anywhere more distant than high Earth orbit has been gathered in by the DSN web. For half a century, when spacecraft phone home, the DSN has always answered the call—and the plan is that it always will.